The present invention relates to an automatic putting-out apparatus and particularly to an automatic putting-out apparatus which can be used to control room heating by automatically interrupting combustion when the room temperature reaches a predetermined temperature.
A variety of fire putting-out means have been developed so far in the field of room heating, which can put off heating apparatuses when the room temperature reaches a certain level.
As an example, a Japanese patent publication 41/12269 discloses a heating controller wherein the flow of fuel through a main combustion device is controlled by operating a control valve in a bleed line to adjust the pressure depending on the room temperature. This system, however, is not suited for practical use because it includes so many different components like pressure controllers, several valves, lever devices with temperature-responding members and supporting means to maintain the lever devices at neutral position that responding speed is not only slow but also its construction is very complicated and costly.
As another typical type widely used in many countries, there are fire extinguishers based on bimetals in which a power switch is operated based on a bimetal plate to actuate a motor to shift operating load through rotary movement of an eccentric cam to thereby interrupt ignition. This kind of system is also associated with drawbacks in that an electric circuit comprising an connector to operate a motor by bending bimetal through heating based on the difference in thermal expansion of metals is needed and further both a device for interrupting combustion and a mechanism for initiating combustion are required, resulting in complex operation and high manufacturing cost.
Under the circumstances stated above, the present inventors made an intensive effort to develop an automatic putting-out apparatus which is simple in construction and easy in operation to be adapted for practical embodiment and which can contribute to improvement in human health by controlling the levels of harmful gases like carbon monoxide and carbon dioxide in the air in a room where the heater is installed as well as the room temperature within acceptable levels. As the result, an automatic putting-out apparatus which can fulfill the sought desire in spite of a simple structure has been devised.
The present invention takes the advantage of a property of a shape-memory alloy which restores its original shape at the critical temperature intrinsic of the material of the alloy regardless of its ability to deform freely below that temperature to actuate the switching means of the putting-out apparatus in response to a certain elevated temperature. The approximate relation of the accumulation of harmful indoor gases with the room temperature is also used. Thus, the object of the present invention is to provide an automatic putting-out apparatus which is reliable to operate for prevention of overheating or fire and for preserving human health and is simple to construct by using a shape-memory alloy, is manufactured at a low cost mainly because of elimination of electric power and motor and can be operated irrespective of electric power failure.